Unlicensed radiofrequency transmitters operate under constraints imposed by the Federal Communications Commission (FCC). Unlicensed transmitters are commonly used in key fobs for remotely performing various vehicular functions, such as locking or unlocking the doors or hatches of a vehicle, activating or de-activating an alarm, unlatching a door, trunk, or other latching closure, or operating a powered lift gate. Accordingly, vehicles are usually equipped with a wireless receiver to receive signals from key fobs and other transmitters.
Wireless receivers, however, draw electrical power from the battery of a vehicle. To reduce the draw on the battery, receivers can be set to poll periodically, rather than running constantly. During polling, the receiver can activate completely and be placed in a state of increased electrical power usage for the purpose of detecting a signal for a short period of time. Between activations, a controller can place the receiver in a state of low- or no-power usage, conserving the vehicle's battery life.
Thus, the timeliness of a vehicle's response to the manipulation of a key fob (e.g., pressing a button) transmitting a signal can depend on various factors, including signal transmission strength of the wireless transmitter, the duration of transmission of the signal, interference from nearby sources, and synchronicity of polling and signal transmit rates. Responsiveness of the vehicle to signals from a key fob can therefore vary.